It is known from the prior art that some specific types of silanes or siloxanes having surface active groups can provide these properties, in particular spreading properties.
For example, alkylenoxide modified tri- and disiloxanes are already disclosed in U.S. Pat. No. 3,299,112 and exhibit very good spreading properties, especially a high spreading velocity. These compounds are proposed for the use as agricultural sprays without undue foaming of the spray mixture as disclosed in U.S. Pat. No. 5,504,054. Such polyether-siloxanes are e.g. available under tradenames like Silwet L 77 (former trade name of Union Carbide) from GE Bayer Silicones. (see for example R. Wagner, Y. Wu, G. Czichocki, H. v. Berlepsch, F. Rexin, L. Perepelittchenko, Silicon-modified surfactants and wetting: II. Temperature-dependent spreading behaviour of oligoethylene glycol derivatives of heptamethyltrisiloxane, Applied Organometallic Chemistry Vol 13, Issue 3 pages 201-208; 611-620, 1999, John Wiley & Sons, Ltd.).
For example Silwet L 77 has the following formula:(R3SiO)2SiR—R* with R*═—(CH2)n—O—(C2H4O—)5-10—CH3.
EP-A 710500, EP-A 630901 or U.S. Pat. No. 6,489,498 (Goldschmidt) describe mono-functional polyethersiloxanes wherein one endgroup of the polyether is a trialkylsilyl group. DE 41 41 046 (Goldschmidt) describes other trisiloxanes having alkylsulphate groups or salts thereof as side group.
GB 1 520 421 A or EP-A 367381 (Dow Corning) disclose silane or siloxane structures with a hydrophilic group, which does not include polyether groups. The synthesis for these types of silane or siloxane structures utilizes GRIGNARD-reactions based on chloromethyl-trimethylsilane or other silanes.
All of these compounds have one or more disadvantages, i.e. either the spreading properties are not stable under storage at extreme conditions like pH below 5 or above pH 9 and or the spreading effect e.g. the efficiency or the velocity to spread over extended areas is too small. Especially surface active compounds having more than 2 siloxane bonds tends to be unstable at pH values smaller <6 or greater >7.5 are undergoing reactions which lead to non-active compounds in terms of spreading. The manufacturing by GRIGNARD reactions has an significant impact on costs of the precursors.
Compounds having superspreading properties can provide this ability under severe conditions over longer times and they can enhance the action of active substances upon surfaces, wettability of several surfaces like the distribution of plant protection agents on the surfaces of leaves or antifoaming agents or foamstabilizers on the surface of numerous compositions whereby the spreading agent itself can act as defoamer or foam stabilizer.
The expense synthesis going over organometallic coupling reaction like GRIGNARD or WURTZ reactions or expensive precursors like chloromethyl-trimethylsilane imply obviously disadvantages e.g. in costs for a broad application of these compounds.
The surface active compounds in terms of the invention are especially those compounds which have a high resistance against extreme concentrations of proton concentrations, i.e. as well pH values of smaller than 5 and higher than 10. A second feature of these compounds is the ability to spread upon the surface under acidic and basic conditions in a very short time, and maintaining this property over a long time of storage or in the presence of other chemicals.
Furthermore the new compounds can be obtained by a completely new process from cheap intermediates without need for use of organometallic compounds which are expensive and difficult to handle.
Thus the invention provides new structures, new sources of the precursors and new routes of the synthesis for organodisilanes or carbosilanes modified with surface active groups having the ability to maintain its spreading properties over longer time over storage under severe conditions.
Such properties are required in several compositions where active ingredients have to be distributed upon a surface in a short time, especially when used in aqueous solutions to improve the delivery of active ingredients to the surface being treated. The new compounds exhibit properties which are least comparable to the trisiloxane type compounds. However, the trisiloxane compounds may only be used in a narrow pH range, ranging from a slightly acidic pH of 6 to a very mildly basic pH of 7.5. Outside this narrow pH range, the trisiloxane compounds are not stable to hydrolysis undergoing a rapid decomposition. Moreover the new compounds are easy to prepare by a novel process.